307 lines
9.2 KiB
C#
307 lines
9.2 KiB
C#
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// PendingBuffer.cs
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//
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// Copyright (C) 2001 Mike Krueger
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// Copyright (C) 2004 John Reilly
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//
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// This file was translated from java, it was part of the GNU Classpath
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// Copyright (C) 2001 Free Software Foundation, Inc.
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//
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// This program is free software; you can redistribute it and/or
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// modify it under the terms of the GNU General Public License
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// as published by the Free Software Foundation; either version 2
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// of the License, or (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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//
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// Linking this library statically or dynamically with other modules is
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// making a combined work based on this library. Thus, the terms and
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// conditions of the GNU General Public License cover the whole
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// combination.
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//
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// As a special exception, the copyright holders of this library give you
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// permission to link this library with independent modules to produce an
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// executable, regardless of the license terms of these independent
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// modules, and to copy and distribute the resulting executable under
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// terms of your choice, provided that you also meet, for each linked
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// independent module, the terms and conditions of the license of that
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// module. An independent module is a module which is not derived from
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// or based on this library. If you modify this library, you may extend
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// this exception to your version of the library, but you are not
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// obligated to do so. If you do not wish to do so, delete this
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// exception statement from your version.
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using System;
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namespace PdfSharp.SharpZipLib.Zip.Compression
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{
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/// <summary>
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/// This class is general purpose class for writing data to a buffer.
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///
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/// It allows you to write bits as well as bytes
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/// Based on DeflaterPending.java
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///
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/// Author of the original java version: Jochen Hoenicke
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/// </summary>
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internal class PendingBuffer
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{
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#region Instance Fields
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/// <summary>
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/// Internal work buffer
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/// </summary>
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byte[] buffer_;
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int start;
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int end;
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uint bits;
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int bitCount;
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#endregion
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#region Constructors
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/// <summary>
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/// construct instance using default buffer size of 4096
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/// </summary>
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public PendingBuffer()
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: this(4096)
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{
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}
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/// <summary>
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/// construct instance using specified buffer size
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/// </summary>
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/// <param name="bufferSize">
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/// size to use for internal buffer
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/// </param>
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public PendingBuffer(int bufferSize)
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{
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buffer_ = new byte[bufferSize];
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}
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#endregion
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/// <summary>
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/// Clear internal state/buffers
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/// </summary>
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public void Reset()
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{
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start = end = bitCount = 0;
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}
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/// <summary>
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/// Write a byte to buffer
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/// </summary>
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/// <param name="value">
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/// The value to write
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/// </param>
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public void WriteByte(int value)
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{
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#if DebugDeflation
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if (DeflaterConstants.DEBUGGING && (start != 0) )
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{
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throw new SharpZipBaseException("Debug check: start != 0");
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}
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#endif
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buffer_[end++] = unchecked((byte)value);
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}
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/// <summary>
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/// Write a short value to buffer LSB first
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/// </summary>
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/// <param name="value">
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/// The value to write.
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/// </param>
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public void WriteShort(int value)
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{
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#if DebugDeflation
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if (DeflaterConstants.DEBUGGING && (start != 0) )
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{
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throw new SharpZipBaseException("Debug check: start != 0");
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}
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#endif
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buffer_[end++] = unchecked((byte)value);
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buffer_[end++] = unchecked((byte)(value >> 8));
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}
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/// <summary>
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/// write an integer LSB first
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/// </summary>
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/// <param name="value">The value to write.</param>
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public void WriteInt(int value)
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{
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#if DebugDeflation
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if (DeflaterConstants.DEBUGGING && (start != 0) )
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{
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throw new SharpZipBaseException("Debug check: start != 0");
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}
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#endif
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buffer_[end++] = unchecked((byte)value);
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buffer_[end++] = unchecked((byte)(value >> 8));
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buffer_[end++] = unchecked((byte)(value >> 16));
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buffer_[end++] = unchecked((byte)(value >> 24));
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}
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/// <summary>
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/// Write a block of data to buffer
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/// </summary>
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/// <param name="block">data to write</param>
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/// <param name="offset">offset of first byte to write</param>
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/// <param name="length">number of bytes to write</param>
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public void WriteBlock(byte[] block, int offset, int length)
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{
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#if DebugDeflation
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if (DeflaterConstants.DEBUGGING && (start != 0) )
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{
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throw new SharpZipBaseException("Debug check: start != 0");
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}
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#endif
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System.Array.Copy(block, offset, buffer_, end, length);
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end += length;
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}
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/// <summary>
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/// The number of bits written to the buffer
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/// </summary>
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public int BitCount
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{
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get
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{
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return bitCount;
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}
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}
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/// <summary>
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/// Align internal buffer on a byte boundary
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/// </summary>
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public void AlignToByte()
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{
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#if DebugDeflation
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if (DeflaterConstants.DEBUGGING && (start != 0) )
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{
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throw new SharpZipBaseException("Debug check: start != 0");
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}
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#endif
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if (bitCount > 0)
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{
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buffer_[end++] = unchecked((byte)bits);
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if (bitCount > 8)
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{
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buffer_[end++] = unchecked((byte)(bits >> 8));
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}
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}
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bits = 0;
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bitCount = 0;
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}
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/// <summary>
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/// Write bits to internal buffer
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/// </summary>
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/// <param name="b">source of bits</param>
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/// <param name="count">number of bits to write</param>
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public void WriteBits(int b, int count)
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{
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#if DebugDeflation
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if (DeflaterConstants.DEBUGGING && (start != 0) )
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{
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throw new SharpZipBaseException("Debug check: start != 0");
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}
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// if (DeflaterConstants.DEBUGGING) {
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// //Console.WriteLine("writeBits("+b+","+count+")");
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// }
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#endif
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bits |= (uint)(b << bitCount);
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bitCount += count;
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if (bitCount >= 16)
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{
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buffer_[end++] = unchecked((byte)bits);
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buffer_[end++] = unchecked((byte)(bits >> 8));
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bits >>= 16;
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bitCount -= 16;
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}
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}
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/// <summary>
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/// Write a short value to internal buffer most significant byte first
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/// </summary>
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/// <param name="s">value to write</param>
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public void WriteShortMSB(int s)
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{
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#if DebugDeflation
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if (DeflaterConstants.DEBUGGING && (start != 0) )
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{
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throw new SharpZipBaseException("Debug check: start != 0");
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}
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#endif
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buffer_[end++] = unchecked((byte)(s >> 8));
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buffer_[end++] = unchecked((byte)s);
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}
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/// <summary>
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/// Indicates if buffer has been flushed
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/// </summary>
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public bool IsFlushed
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{
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get
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{
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return end == 0;
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}
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}
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/// <summary>
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/// Flushes the pending buffer into the given output array. If the
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/// output array is to small, only a partial flush is done.
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/// </summary>
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/// <param name="output">The output array.</param>
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/// <param name="offset">The offset into output array.</param>
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/// <param name="length">The maximum number of bytes to store.</param>
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/// <returns>The number of bytes flushed.</returns>
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public int Flush(byte[] output, int offset, int length)
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{
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if (bitCount >= 8)
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{
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buffer_[end++] = unchecked((byte)bits);
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bits >>= 8;
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bitCount -= 8;
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}
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if (length > end - start)
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{
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length = end - start;
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System.Array.Copy(buffer_, start, output, offset, length);
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start = 0;
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end = 0;
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}
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else
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{
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System.Array.Copy(buffer_, start, output, offset, length);
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start += length;
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}
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return length;
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}
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/// <summary>
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/// Convert internal buffer to byte array.
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/// Buffer is empty on completion
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/// </summary>
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/// <returns>
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/// The internal buffer contents converted to a byte array.
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/// </returns>
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public byte[] ToByteArray()
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{
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byte[] result = new byte[end - start];
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System.Array.Copy(buffer_, start, result, 0, result.Length);
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start = 0;
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end = 0;
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return result;
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}
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}
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}
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